Effects of Rich in Β-Glucans Edible Mushrooms on Aging Gut Microbiota Characteristics: An In Vitro Study

Alterations of gut microbiota are evident during the aging process. Prebiotics may restore the gut microbial balance, with β-glucans emerging as prebiotic candidates. This study aimed to investigate the impact of edible mushrooms rich in β-glucans on the gut microbiota composition and metabolites by using in vitro static batch culture fermentations and fecal inocula from elderly donors (n = 8). Pleurotus ostreatus, P. eryngii, Hericium erinaceus and Cyclocybe cylindracea mushrooms derived from various substrates were examined. Gut microbiota composition (quantitative PCR (qPCR)) and short-chain fatty acids (SCFAs; gas chromatography (GC)) were determined during the 24-h fermentation. P. eryngii induced a strong lactogenic effect, while P. ostreatus and C. cylindracea induced a significant bifidogenic effect (p for all <0.05). Furthermore, P. eryngii produced on wheat straw and the prebiotic inulin had comparable Prebiotic Indexes, while P. eryngii produced on wheat straw/grape marc significantly increased the levels of tested butyrate producers. P. ostreatus, P. eryngii and C. cylindracea had similar trends in SCFA profile; H. erinaceus mushrooms were more diverse, especially in the production of propionate, butyrate and branched SCFAs. In conclusion, mushrooms rich in β-glucans may exert beneficial in vitro effects in gut microbiota and/or SCFAs production in elderly subjects.

Effect of banana consumption on faecal microbiota: a randomised, controlled trial

Banana is a widely consumed fruit, which contains considerable amounts of potential prebiotic indigestible carbohydrates. In our randomised, controlled trial we aimed to evaluate the in vivo prebiotic effect of banana consumption on faecal microbiota. Thirty-four healthy women participated in the study, having Body Mass Index (BMI) 24-30 kg/m(2), age 19-45 years, without history of gastrointestinal disease and no antibiotic and other medication use two months prior the initiation and during the study. All women were asked to maintain their usual dietary habits for 60 days and they were randomly assigned to consume twice a day a pre-meal snack, either one medium banana, or one cup of banana-flavoured drink or one cup of water (control group). Stool samples were collected at baseline, on days 30 and 60 of intervention for enumeration of total anaerobes, bifidobacteria and lactobacilli by plate count techniques, as well as for pH and short chain fatty acids (SCFAs) measurement. Gastrointestinal symptoms were also recorded. Mean bifidobacterial levels were increased only in the banana group both at 30 and 60 days of intervention, but this change did not reach a statistical significance. No significant overall differences in the total concentrations and molar ratios of SCFAs were detected according to dietary intervention. Analysis of the gastrointestinal symptoms records revealed significantly lower bloating levels in the banana group, compared to controls, at 26-35 days (p = 0.009) and 51-60 days (p = 0.010). Banana consumption had also no adverse effects on evacuation patterns. We concluded that daily consumption of bananas is a well-tolerated eating behaviour, which may induce bifidogenesis in healthy women experiencing body weight problems.

Fermentation of Pleurotus ostreatus and Ganoderma lucidum mushrooms and their extracts by the gut microbiota of healthy and osteopenic women: potential prebiotic effect and impact of mushroom fermentation products on human osteoblasts

Recent data have highlighted the role of the gut microbiota and its several metabolites in maintaining bone health. Thus, gut microbiota manipulation, e.g., by prebiotics, might offer a plausible target in the fight against bone degenerative diseases. This study aimed (a) to investigate the in vitro prebiotic potential of Ganoderma lucidum and Pleurotus ostreatus mushrooms in healthy and osteopenic women and (b) to explore the impact of mushroom fermentation products on human osteoblasts. G. lucidum LGAM 9720 and P. ostreatus IK 1123 lyophilized mushroom-powders (2% w/v) and their hot-water extracts (1% w/v) were fermented in a 24 h static batch culture model by using faecal inocula from healthy (n = 3) or osteopenic (n = 3) donors. Gut microbiota analysis (qPCR) and measurement of short chain fatty acids (SCFAs) were performed during fermentation, and 24 h-prebiotic indexes were calculated. Evaluation of the effects of fermentation products on bone metabolism parameters (OPG: osteoprotegerin; and RANKL: receptor activator of nuclear factor kappa B ligand) in osteoblast cultures was also performed. Our data suggest that the origin of the gut microbiota inoculum plays a major role in the viability of osteoblasts. The treatments using P. ostreatus mushroom-powder and G. lucidum mushroom-extract had positive effects based on gut microbiota and SCFA analyses. Both mushrooms exhibited lower RANKL levels compared to controls, whereas their extracts tended to enhance the osteoblastic activity. In conclusion, mushrooms that are rich in beta-glucans may exert beneficial in vitro effects on bone physiology by alterations in the gut microbiota and/or SCFA production.

Screening fecal enterococci from Greek healthy infants for susceptibility to antimicrobial agents

Enterococci are among the first lactic acid bacteria to colonize the neonatal gastrointestinal tract, but they are also characterized as significant nosocomial pathogens. The aim of this study was to investigate the incidence of antibiotic resistance in enterococci isolated from neonates' gut microbiota as well as the presence of genetic determinants encoding for certain antibiotic resistance traits. A total of 263 fecal samples derived from 97 infants were collected on day 4, 30, and 90 after delivery. Enterococcus faecalis was the most frequently identified species (54.6%) followed by E. faecium, while E. casseliflavus/E. flavescens and E. gallinarum were also traced. The isolates were examined for their resistance to 12 antibiotics. Rifampicin resistance was the highest observed (53.2%), followed by resistance to tetracycline (42.0%), erythromycin (35.7%), and vancomycin (11.2%). Multiresistant strains were highly prevalent. Only intrinsic vancomycin resistance (vanC1 and vanC2/C3) was traced. The ermB gene was detected in 49 out of 96 erythromycin-resistant isolates, while tet genes were detected in 51 out of 113 tetracycline-resistant strains, with tet(L) being the most frequently observed. In conclusion, antibiotic-resistant enterococci are already established in the fecal microbiota of healthy neonates, from the first days of an infant's life.

Antibiotic resistance in faecal microbiota of Greek healthy infants

Increasing use of antibiotics for the treatment of infectious diseases and also for non-therapeutic reasons (agriculture, animal husbandry and aquaculture) has led to the increasing incidence of antibiotic resistance and the ineffectiveness of antimicrobial treatment. Commensal intestinal bacteria are very often exposed to the selective pressure of antimicrobial agents and may constitute a reservoir of antibiotic resistance determinants that can be transferred to pathogens. The present study aimed to investigate the antibiotic susceptibility profile and the presence of selected resistance genes in cocci isolated from the faecal microbiota of 35 healthy, full-term infants at 4, 30 and 90 days after delivery. A total of 148 gram-positive, catalase-negative cocci were isolated and tested for susceptibility to 12 different antibiotics by disk-diffusion technique. Multiplex PCR analysis was performed for the identification of Enterococcus spp. isolates and the simultaneous detection of vancomycin-resistance genes. PCR-based methodology was used also for identification of tetracycline and erythromycin resistance determinants. Identification results indicated E. faecalis as the predominant species (81 strains), followed by E. faecium, E. casseliflavus/E. flavescens and E. gallinarum. High prevalence of resistance to tetracycline (39.9%), erythromycin (35.1%), vancomycin (19.6%) and to nucleic acid synthesis inhibitors was detected. PCR data revealed 24 out of 52 erythromycin-resistant isolates carrying the ermB gene and 32 out of 59 tetracycline-resistant strains carrying tet genes, with tet(L) determinant being the most frequently detected. Only intrinsic vancomycin resistance (vanC1 and vanC2/C3) was reported among tested isolates. In conclusion, erythromycin and tetracycline acquired resistant traits are widespread among faecal cocci isolates from Greek, healthy infants under no apparent antimicrobial selective pressure.

Impact of a jelly containing short-chain fructo-oligosaccharides and Sideritis euboea extract on human faecal microbiota

In this randomized, double-blinded, placebo-controlled clinical study we aimed to evaluate the in vivo prebiotic effects of a functional food containing short-chain fructo-oligosaccharides (sc-FOS) and Sideritis euboea extract on human faecal microflora. Sixty-four healthy volunteers 26 men and 38 women (age range: 22-51) were assigned to consume daily a jelly containing 5 g sc-FOS and 0.3 g S.euboea extract or a placebo for 30 d. Stool samples were collected prior to the study on day 15 and 30 of intervention and 2 weeks after. Enumeration of faecal bacteria was performed by plate count techniques. Gastrointestinal side effects were recorded during the treatment period. Data demonstrated a significant bifidogenic effect of the experimental jelly compared to the placebo after 15 [9.54+/-0.83 vs. 8.57+/-1.91 log(10)CFU (colony forming units)/g faeces P=0.001] and 30 d of consumption (9.34+/-1.04 vs. 8.57+/-1.98 log(10)CFU/g faeces P=0.027) and significant higher bifidobacterial levels in the sc-FOS+extract group 2 weeks after the end of intervention (9.33+/-0.61 vs. 8.79+/-0.93 log(10)CFU/g faeces P=0.015). A trend for greater flatulence was detected after 15 d of functional food ingestion with no further differences in gastrointestinal symptoms. In conclusion the daily intake of a jelly containing sc-FOS and S.euboea extract is well-tolerated and demonstrated significant bifidogenic properties in healthy volunteers consuming their usual diets.

Screening for faecal contamination in primary schools in Crete, Greece

BACKGROUND

Hygienic conditions in primary schools are a major concern for both governmental organizations and families. Particularly, the occurrence of faecal indicators on children's hands and various school surfaces has been associated with increased risk of diarrhoeal diseases. The presence of faecal streptococci on environmental surfaces and children's hands and the possible correlation with socio-economic factors were examined.

METHODS

Overall, 1956 samples from hands and 1470 samples from surfaces were collected from 20 primary schools in Heraklion, Crete, Greece.

RESULTS

Faecal streptococci were found at 52.9% of children's hands and at 16.7% of other surfaces. Children, who had parents with the highest education level (>12 years), had the lowest percentage (48.8%) of faecal contamination on their hands. Furthermore, boys exhibited higher levels of hands contamination compared with girls. Among the environmental surfaces examined, the school canteen reception was the most contaminated area.

CONCLUSION

High faecal contamination was detected in primary schools in the examined region. Children's hands were highly infected (52.9%), while boys exhibited higher levels of contamination. The educational level of parents correlated well with the contamination of children's hands.

Immunomodulating Activity of Pleurotus eryngii Mushrooms Following Their In Vitro Fermentation by Human Fecal Microbiota

Recent studies have revealed the crucial role of several edible mushrooms and fungal compounds, mainly polysaccharides, in human health and disease. The investigation of the immunomodulating effects of mushroom polysaccharides, especially β-glucans, and the link between their anticancer and immunomodulatory properties with their possible prebiotic activity on gut micro-organisms has been the subject of intense research over the last decade. We investigated the immunomodulating effects of Pleurotus eryngii mushrooms, selected due to their high β-glucan content, strong lactogenic effect, and potent geno-protective properties, following in vitro fermentation by fecal inocula from healthy elderly volunteers (>60 years old). The immunomodulating properties of the fermentation supernatants (FSs) were initially investigated in U937-derived human macrophages. Gene expression as well as pro- (TNF-α, IL-1β) and anti-inflammatory cytokines (IL-10, IL-1Rα) were assessed and correlated with the fermentation process. The presence of P. eryngii in the fermentation process led to modifications in immune response, as indicated by the altered gene expression and levels of the cytokines examined, a finding consistent for all volunteers. The FSs immunomodulating effect on the volunteers’ peripheral blood mononuclear cells (PBMCs) was verified through the use of cytometry by time of flight (CyTOF) analysis.

Fermentation Supernatants of Pleurotus eryngii Mushroom Ameliorate Intestinal Epithelial Barrier Dysfunction in Lipopolysaccharide-Induced Caco-2 Cells via Upregulation of Tight Junctions

In recent years, modulation of gut microbiota through prebiotics has garnered interest as a potential to ameliorate intestinal barrier dysfunction. The aim of the study was to examine the in vitro effect of fermentation supernatants (FSs) from rich in β-glucan Pleurotus eryngii mushrooms on the expression levels of tight junctions (TJs) genes in Caco-2 cells stimulated by bacterial lipopolysaccharides (LPS). Mushrooms were fermented using fecal inocula in an in vitro batch culture model. Caco-2 cells were subjected to LPS and FS treatment under three different conditions: pre-incubation with FS, co- and post-incubation. Reverse transcription PCR was applied to measure the expression levels of zonulin-1, occludin and claudin-1 genes. FSs from P. eryngii mushrooms led to a significant upregulation of the TJs gene expression in pre-incubation state, indicating potential preventive action. Down-regulation of all TJs gene expression levels was observed when the cells were challenged with LPS. The FS negative control (gut microbiota of each donor with no carbohydrate source) exhibited a significant upregulation of TJs expression levels compared to the cells that were challenged with LPS, for all three conditions. Overall, our data highlighted the positive and potential protective effects of P. eryngii mushrooms in upregulation of TJs’ genes.

Genoprotective activity of the Pleurotus eryngii mushrooms following their in vitro and in vivo fermentation by fecal microbiota

Pleurotus eryngii mushrooms are commercially cultivated and widely consumed due to their organoleptic properties, and the low caloric and high nutritional value. In addition, they contain various biologically active and health-promoting compounds; very recently, their genoprotective effect in Caco-2 cells after their fermentation by the human fecal microbiota was also documented. In the current study, the effect of P. eryngii pre- and post-fermentation supernatants in micronuclei formation was evaluated in human lymphocytes. In addition, the genoprotective properties of increasing concentrations of aqueous extracts from P. eryngii mushrooms (150, 300, 600 mg/kg) against the cyclophosphamide-induced DNA damage were studied in young and elderly female and male mice in bone marrow and whole blood cells. The ability of the highest dose (600 mg/kg) to regulate the main cellular signaling pathways was also evaluated in gut and liver tissues of female animals by quantifying the mRNA expression of NrF2, Nfkβ, DNMT1, and IL-22 genes. P. eryngii post-fermentation, but not pre-fermentation, supernatants were able to protect human lymphocytes from the mitomycin C-induced DNA damage in a dose-dependent manner. Similarly, genoprotection was also observed in bone marrow cells of mice treated by gavage with P. eryngii extract. The effect was observed in all the experimental groups of mice (young and elderly, male and female) and was more potent in young female mice. Overexpression of all genes examined was observed in both tissues, mainly among the elderly animals. In conclusion, P. eryngii mushrooms were shown to maintain genome integrity through protecting cells from genotoxic insults. These beneficial effects can be attributed to their antioxidant and immunomodulatory properties, as well as their ability to regulate the cell's epigenetic mechanisms and maintain cell homeostasis.

Knowledge of Dietitians on Gut Microbiota in Health-An Online Survey of the European Federation of the Associations of Dietitians (EFAD)

Explorations of current knowledge of dietitians about gut-health interconnection and the role of diet in gut microbiota manipulation are rather scarce in the literature. In this online survey we assessed the perceived and current knowledge of dietitians across Europe about gut microbiota and systemic health, nutrition as a modulator of the gut ecosystem, and the role of probiotics and prebiotics. Pre-graduate dietetic students and other professionals were also invited to participate. A total of 179 full responses were recorded (dietitians, n = 155), mainly from Southern and Western regions. Most participants (>78.0%) reported an average to good level of perceived knowledge, with significant positive correlations between perceived and current knowledge in all sections and overall (p for all <0.05). Nevertheless, a rather low current knowledge scoring of participants about probiotics and prebiotics was observed. Features such as being a dietitian, having a higher educational level as dietitian and working in an academic/research setting were usually associated with higher current knowledge. Further analysis revealed that dietitians had a trend for higher scoring about probiotics and prebiotics compared to pre-graduate students or other professionals. Moreover, for dietitians, working in an academic or research setting was an independent factor for scoring in the highest quartile in all tested sections and overall (p for all <0.05). In conclusion, this online survey shed some light on the current knowledge of dietitians across Europe about gut microbiota parameters, including dietary modulation, highlighting in parallel possible knowledge determinants. Potential areas for future educational efforts in this rather unexplored field were indicated.

Inhibition of Listeria monocytogenes Growth, Adherence and Invasion in Caco-2 Cells by Potential Probiotic Lactic Acid Bacteria Isolated from Fecal Samples of Healthy Neonates

Lactic acid bacteria (LAB) isolated from healthy humans may prove an effective tool against pathogen growth, adherence and invasion in intestinal epithelial cells. This study aimed to evaluate the antilisterial properties of LAB isolated from fecal samples of healthy neonates. Forty-five LAB strains were tested for their antimicrobial activity against ten Listeria monocytogenes strains with spot-on-lawn and agar-well diffusion assays, and ten lactobacilli strains were further assessed for their inhibitory effect against adherence and invasion of Caco-2 cells by L. monocytogenes EGDe. Inhibition was estimated in competition, exclusion or displacement assays, where lactobacilli and L. monocytogenes were added to Caco-2 monolayers simultaneously or 1 h apart from each other. Inhibition of L. monocytogenes growth was only displayed with the spot-on-lawn assay; cell-free supernatants of lactobacilli were not effective against the pathogen. Lactobacillus (L.) paragasseri LDD-C1 and L. crispatus LCR-A21 were able to adhere to Caco-2 cells at significantly higher levels than the reference strain L. rhamnosus GG. The adherence of L. monocytogenes to Caco-2 cells was reduced by 20.8% to 62.1% and invasion by 33.5% to 63.1% during competition, which was more effective compared to the exclusion and displacement assays. These findings demonstrate that lactobacilli isolated from neonatal feces could be considered a good candidate against L. monocytogenes.

Does Yogurt Enriched with Platelet-Activating Factor Inhibitors from Olive Oil By-Products Affect Gut Microbiota and Faecal Metabolites in Healthy Overweight Subjects? (A randomized, parallel, three arm trial.)

OBJECTIVE

The effect of the daily consumption of a low-fat yogurt (150 g) enriched with Platelet-Activating Factor receptor (PAF-R) antagonists, or the plain one, on gut microbiota and faecal metabolites was investigated in healthy overweight subjects.

METHODS

A randomized, three-arm, double-blind, placebo-controlled, parallel-group study was performed that lasted 8 weeks. Blood and stools were collected and analyzed before and after the intervention.

RESULTS

Our findings revealed that the intake of the enriched yogurt resulted in a significant increase in the levels of Bifidobacterium spp., Clostridium perfringens group and Firmicutes-to-Bacteroidetes (F/B) ratio. On the other hand, a significant increase in the levels of Lactobacillus and C. perfringens group was detected after the intake of the plain yogurt. The increase in the levels of C. perfringens group was inversely associated with the plasma catabolic enzyme of PAF, namely LpPLA2 (lipoprotein-associated phospholipase A2), a cardiovascular risk marker that has been linked with inflammation and atherosclerosis. Moreover, in the enriched with PAF-R antagonists yogurt group, the increased levels of C. perfringens group were also associated with lower PAF action assessed as ex vivo human platelet-rich plasma (PRP) aggregation. Additionally, a higher % increase in molar ratio of Branched Short Chain Fatty Acids (BSCFAs) was detected for both yogurt groups after the 8 week-intervention compared to control. The consumption of the enriched yogurt also resulted in a significant drop in faecal caproic levels and a trend for lower ratio of butyrate to total volatile fatty acids (VFAs) compared to baseline levels.

CONCLUSION

Yogurt consumption seems to favorably affect gut microbiota while its enrichment with PAF-R antagonists from olive oil by-products, may provide further benefits in healthy overweight subjects.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (NCT02259205).

Correction: Boulaka et al. Genoprotective Properties and Metabolites of β-Glucan-Rich Edible Mushrooms Following Their In Vitro Fermentation by Human Faecal Microbiota. Molecules 2020, 25, 3554

The authors wish to add the following information to the Authors and Affiliation section of our paper published in Molecules [...].

Attitudes and Practices of Dietitians Regarding Gut Microbiota in Health-An Online Survey of the European Federation of the Associations of Dietitians (EFAD)

Explorations of the current attitudes and practices of dietitians regarding the gut microbiota in health are scarce. In this online survey, we assessed the attitudes and practices of dietitians across Europe concerning gut microbiome parameters and the manipulation of the gut microbiota. Pre-graduate dietetic students and other professionals were also invited to participate. The potential interest and preferences of the participants for future educational initiatives about the gut microbiota and the educational resources used were further explored. A total of 179 full responses were recorded (dietitians, n = 155), mainly from the southern and western regions. Most of the participants (>90.0%) believed that probiotics and prebiotics have a place in nutritional practice and that fermented foods with live microbial cultures should be a part of food-based dietary guidelines. A strong belief in the beneficial roles of probiotics and prebiotics in some health situations was also reported among the participants. Most of the dietitians recognised the importance of gut microbiota manipulation and advised the use of probiotics and prebiotics in dietary practice, and they felt quite confident applying the relevant information in their daily practice. Nevertheless, misconceptions were identified, and further guideline-oriented education is necessary. The interest in future e-learning initiatives was high among the participants, and the sources of knowledge, educative formats, and potential areas for further educational efforts were indicated.